1. Field of the Invention
The present invention relates to a measuring carriage for a linear measuring system which comprises a tubular protective housing having opposite sides, the tubular housing defining an interior chamber and one of the housing sides defining a slot sealed by sealing lips, and a measuring rod carrying a measuring scale arranged in the interior housing chamber. The measuring carriage comprises a measurement sensing entrainment block arranged outside the housing adjacent the one housing side, the block comprising a tongue projecting into the interior housing chamber through the slot, means for generating electrical signals derived from sensing the measuring scale by the entrainment block, carrier means in the interior housing chamber for supporting the signal generating means, support means for the carrier means, the tongue connecting the entrainment block to the support means, a connecting cable attached to, and leading from, the entrainment block, and wires connecting the signal generating means to the connecting cable, the wires passing from the signal generating means to the entrainment block and the connecting cable through a recess in the tongue.
2. Description of the Prior Art
Measuring carriages of this type may be used in connection with various measuring systems, including an absolute measuring scale, an incremental measuring scale or a combination thereof, especially systems in which reference and/or control marks are provided on a measuring rod in addition to an incremental measuring scale, and wherein the scale and marks are sensed according to the selected measuring system by well known generally opto-electronic, particularly photoelectric, capacitative, inductive or magnetic sensing principles. For this purpose, suitable devices are mounted on one or more carriers for generating measuring and/or position-indicating electric signals. Opto-electronic sensing devices usually include illuminating elements which illuminate the scale and photo-receivers, combined with sensing grids in the case of incremental scales, which sense the point on the scale on which they are focussed and generate corresponding read-out signals. The illuminating elements are usually mounted on a plate or like carrier means. The measuring carriage may be guided on the measuring rod for displacement therealong and it is known to arrange the measuring rod in a tubular protective housing, and the sensing or read-out units may be adjustably connected to the measuring carriage and also guided on the measuring rod. Particularly if the carrier means are plates, they may also carry signal shaping means or amplifying stages, in addition to the illuminating and sensing elements.
Regardless of the sensing and read-out system, the carrier means must hold a multiplicity of terminals for the power supply to the illuminating devices, the input of control signals and particularly the output of the measuring signals for transmission to processing, counting and control devices, each terminal having an individual transmission wire connected thereto. Heretofore, the wires were led through a recess in the tongue of the measuring carriage and connected to a connecting plate, and corresponding end wires of the connecting cable were associated with the transmission wires and soldered thereto. The cable is attached to a bore in the entrainment block and the wires are passed through the bore and are soldered to the connecting plate outside the block. Subsequently, the connecting plate is introduced in a recess in the entrainment block. The need for a connecting plate and the proper association of the cable wires with the transmission wires considerably increases the time and skill required for assembling the measuring carriage. When the connecting plate is introduced in the entrainment block, usually through a bottom slot therein, the danger exists that the wires are mixed up and/or damaged. In addition, the connecting plate and the wires leading therefrom to the carrier plates increase the weight of the measuring carriage.